This invention relates, in general, to the corrosion protection of a structure that is exposed to wet, gaseous and/or below-ground environments wherein either water or a thin film of condensed moisture covers at least a portion of the structure. In these types of environments, an electrochemical process, often referred to as corrosion, can destroy the material of the structure.
While undergoing corrosion, the structure has two areas, an anodic site (or anode) where the corrosion occurs and from which electrons flow, and a cathodic site (or cathode) to which the electrons flow. Sacrificial anode devices have been used to prevent the corrosion. A sacrificial anode device includes one or more anodes from which electrons flow into the structure, thereby intentionally corroding the anodes while lowering the potential of the structure to such a value that no anodic sites form, that is, no corrosion occurs. The sacrificial anode device is usually replaced as its anodes near destruction.
The installation or replacement of a typical sacrificial anode device is usually costly and time-intensive, and sometimes requires the interruption of the operation of the system of which the structure to be protected is a part. For example, the replacement of a sacrificial anode device connected to an underwater flexible pipe usually requires raising the flexible pipe out of the water.
Therefore, what is needed is a sacrificial anode device that may be quickly and easily installed or replaced in situ, without moving the structure to be protected or interfering with its normal operation.